Press for cold extrusion of deep-holed or bottomed cylindrical articles

ABSTRACT

In a press including an upper die movable vertically relative to a lower die for the cold extrusion of deep-holed or bottomed cylindrical articles, the lower die contains a die ring for accommodating a solid cylindrical blank or workpiece, and the upper die supports a punch movably displaceable into the die ring. The press includes a guide arrangement to ensure the concentricity of the die ring and punch, and to maintain the central axes of the die ring and punch in axial alignment. The guide arrangement also is movable displaceable so that the product being formed can move upwardly about the punch without interference.

United States Patent 1 Suzuki et al.

1 1 PRESS FOR COLD EXTRUSION OF DEEP-HOLED OR BOTTOMED CYLINDRICALARTICLES [75] Inventors: Takamitsu Suzuki; Akio Takahashi;

Shunichi Oya; Mamoru Okamoto, all of Aichi-ken, Japan [73] Assignee:Toyota Jidosha Kogyo Kabushiki Kaisha, Toyota-shi, Aichi-ken, Japan 22Filed: May 30,1973

21 Appl. No.: 365,058

[30] Foreign Application Priority Data Feb. 6, 1973 Japan 48-14246 [52]U.S. Cl 72/267, 72/273, 72/352, 72/456 [51] Int. Cl. B2lc 3/18 [58]Field of Search 72/267, 352, 273, 456, 72/257 [56] References CitedUNITED STATES PATENTS 1,588,246 6/1926 Lyman 72/267 1 Jan. 21, 19759/1940 Traut 72/267 Primary ExaminerC. W. Lanham AssistantExaminer-Robert M. Rogers Attorney, Agent, or Firm-Toren, McGeady andStanger [57] ABSTRACT In a press including an upper die movablevertically relative to a lower die for the cold extrusion of deepholedor bottomed cylindrical articles, the lower die contains a die ring foraccommodating a solid cylindrical blank or workpiece, and the upper diesupports a punch movably displaceable into the die ring. The pressincludes a guide arrangement to ensure the concentricity of the die ringand punch, and to maintain the central axes of the die ring and punch inaxial alignment. The guide arrangement also is movable displaceable sothat the product being formed can move upwardly about the punch withoutinterference.

7 Claims, 6 Drawing Figures PRESS FOR COLD EXTRUSION OF DEEP-HOLED ORBOTTOMED CYLINDRICAL ARTICLES BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to a press for cold extrudingdeep-holed or bottomed cylindrical articles having a length-to-diameterratio of four or more, from solid cylindrical blanks.

2. Description of the Prior Art Generally it has been very difficultwith conventional presses of this character to form deep-holed orhottomed cylindrical articles with a high degree of precision, since thepunches tend to buckle because of their free length during punchingoperation and the punches are also easily distorted under eccentric loaddue to endwise tilting of the workpieces.

SUMMARY OF THE INVENTION Therefore, the present invention has for itsobject to eliminate the defects experienced in the past by ensuring theconcentricity of parts effecting the pressing action, as well asmaintaining the center axis of the punch ter at its upper end forming aneck 9 concentric with and die in parallel and by reducing the freelength of the punch.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which there are illustrated and described preferredembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a vertical sectional view of one embodiment of the invention;

FIGS. 2 and 3 are fragmentary sectional views of the press of FIG. I indifferent positions of an operational cycle;

FIG. 4 is a perspective view showing the detail of a punch guide;

FIG. 5 is a vertical sectional view of another embodiment of theinvention; and

FIG. 6 is a graph showing the dimensional accuracy of an article formedin accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION In the drawings, and particularlyin FIGS. 1 to 3, a press is illustrated embodying the present inventionand consisting of a lower die 1 and an upper die 10 movable verticallytoward and away from the lower die. The lower die 1 includes a dieholder 2 laterally enclosing a support base 3. A die spacer 4 rests onthe upper end of the support base 3 and supports a die case 5 laterallyenclosing a die ring 6. As shown in FIG. 1, a solid cylindrical blank Ais positioned within the die ring 6. Within the support base 3, the diespacer 4, and the die ring 6, a knockout 7 is arranged for movement inthe upward direction by a hydraulic pressure device or other liftingmember for removing the formed article from the die ring. On top of thedie holder 2, stopper blocks 8 are mounted, each having an upper surfaceoriented at right angles to the vertical center axis of the lower die.The die case 5 has a reduced outside diamethe center axis and projectingupwardly above the die holder 2.

The upper die 10 has a cylindrical guide member 1] located above andconcentric to the die ring 6. Adjacent its lower end, a flange 12 issecured to and later ally encircles the lower portion of the guidemember 11. The flange 12 is attached to the lower ends of verticallymovable pistons 15 of cylinders 14, and the cylinders in turn are fixedto a press ram 13 which is adapted to move up and down. Stopper blocks16 are fixed to the underside of the flange l2 opposite the stopperblocks 8 on the lower die 1. The underside of each stopper block 16 isin a plane normal to the vertical center axis of the upper die 10. Thecylinders 14 are supplied with a fluid and normally force the pistons 15downward. Thus, when the press ram 13 ascends or descends, the mutualrelation between the pistons 15 and cylinders 14 causes the guide member11 to rise or fall. When the press ram 13 descends, the stopper blocks16 are brought into contact with the stopper blocks 8 and closer contactis ensured by increasing the hydraulic pressure in the cylinders 14.Lining the interior of the guide member 11 are two thrust ball bearingsl7, 18, one positioned above the other.

Within the guide member 11 and extending along the center axis of theupper die 10 is a stepped punch 20, which is dependently supported fromthe press ram 13 by a mounting member 19. The lower end of the punch 20has a smaller diameter portion 24 as compared to its larger diameterupper portion 21. A ring 22 is secured about the larger diameter upperportion 21 of the punch 20 in such a manner that its outer lateralsurface can slide along the bearing 17 to ensure the concentricity ofthe punch 20 with respect to the guide member 11. The inside diameter ofthe guide member 11 is increased at its lower end 23 to an extentsufficient to receive snugly the neck 9 of the die case 5. The lower,smaller diameter portion 24 of the punch 20 extends through a punchguide assembly 28, which consists of a punch guide case 25 arranged toslide up and down along the bearing 18, a punch guide 26 surrounding andin sliding contact with the punch 20, and an adjust screw 27 forcoupling the guide and guide case together.

As shown in FIG. 4, the punch guide 26 has the form of an invertedtruncated cone and contains a plurality of longitudinal slits 29 whichextend alternately from the opposite ends to permit adjustment of theinside diameter. The slits extend in the axial direction of the punchbut do not extend for the full length of the punch guide. The interiorof the adjust screw 27 is also coneshaped for a collet-type engagementwith the punch guide 26. By means of the adjust screw 27 the clearancebetween the punch 20 and the punch guide 26 is made equal to thediametral expansion of the punch that is caused by the elasticity of thepunch itself during the forming operation.

Thus, when the press ram 13 is in the up position, as shown in FIG. 1,the guide member 11 and punch guide assembly 28 are also raised by meansof the cylinders 14 and pistons 15. Further, the knockout 7 is in thedown position. A solid cylindrical blank A is placed in the die ring 6.As the forming operation is initiated, the press is started, and the ram13 descends. As the lower end of the punch moves downwardly with the ramto a position short of contact with the workpiece A, as in FIG. 2, theenlarged bore portion 23 of the guide member 11 fits around the neck 9of the die case to ensure the axial alignment of the punch 20 and diering 6. Next, the stopper blocks 8, 16 come into contact, and from thenthe hydraulic pressure by the cylinders 14 is increased as the press ram13 descends to assure the axial alignment of the upper die 10 and thelower die 1. At this time the assembly 28 is positioned at the lower endof the bearing 18 and slightly above the lower end of the punch. As thepress ram 13 continues its downward movement, the relative sliding ofthe ring 22 and the bearing 17 enables the punch 20 to contact theworkpiece A and start its cold extrusion. Practically the entire freelength of the lower, smaller diameter portion 24 of the punch 20 isguided by the assembly 28 without any axial distortion midway of thepunch and accordingly, the workpiece A is forced to assure a bottomedcylindrical form B having a bore corresponding to the diameter of thepunch and also a tubular formed lateral part C in close contact with thepunch surface. As the forming operation progresses, the tubular formedpart C increases in length. Consequently, the assembly 28 is graduallypushed upwardly by the upper end of the part C sliding along the bearing18, preventing distortion of the punch 20 while not interfering with theextruding operation. Finally, as shown in FIG. 3, the assembly 28reaches the upper end of the bearing 18 as the punch 20 reaches thelower limit of its stroke, and the forming operation is completed. Inthe return to the starting position, the press ram 13 moves upwardly andthe punch 20 and cylinders 14 move with it, however, the assembly 28remains in the same position guiding the punch as it is withdrawn fromthe cylindrical article B. Next, the guide member 11 is raised by theengagement between the lower parts of the cylinders and the largerdiameter portions of their pistons. When the ram 13 has returned to itsinitial position, the knockout 7 is moved upwardly and pushes the formedarticle B out of the die ring. Accordingly, one complete operating cycleis concluded.

FIG. 5 shows another embodiment of the present invention in which thepunch guide assembly 28 is allowed to move upwardly as the press ram 13descends. Unlike the embodiment illustrated in FIGS. 1 to 3, this one isprovided with pistons 30 which are accommodated in cylinders 14 but arecapable of contacting, at their lower ends, stopper blocks 8 of a dieholder 2. Each piston 30 has a rack 31 formed on one side. Guide member11 is also formed with racks 32 on each of its exterior sides. The case25 of the assembly 28 is fitted within the guide member, and thecombination of the guide member 11 and assembly 28 is slidable relativeto a flange 12 via a slide ball bearing 33 in the flange. Each pair ofadjacent racks 31, 32 are engaged with one pair of pinions 35, 36supported from the press ram 13 by a member 34. i

This second embodiment operates in the following way. At thecommencement of a forming cycle, the press ram 13 descends, bringing thepistons 30 into contact with the stopper blocks 8 immediately before thestart of extrusion. Then, the pinions 35, 36 roll downwardly in meshwith the racks 31 of the pistons 30, and through the racks 32 and theirengagement with the pinions the assembly 28 and bearing 17 are raisedtogether with the guide member 11 along the bearing 33 of the flange 12.This positively keeps the assembly 28 from interfering with the skirtingup of the workpiece around the punch during the extruding operation. Thedimensions of the racks 31, 32 and pinions 35, 36 are so chosen thatthey can raise the assembly 28 as slowly as possible within the rate atwhich the assembly is kept away from the article being formed from theworkpiece.

The dimensional accuracy of a cylindrical article formed by extrusionthrough such embodiments is graphically represented in FIG. 6. Thecylindrical article with a center axis a has a hollow or hole whose axisb is off center by less than 0.05 mm per mm of the depth of the hole.Thus, it will be appreciated that a very good concentricity is attainedwith practically negligible eccentricity. As compared with the centralaxis c of the hole of a conventionally fabricated article represented bya broken line, that of the article according to this invention has aneccentricity of only about onefourth that of the former despite the factthat the latter has a hole more than twice as deep.

As will be obvious from the foregoing description, it is possible withthe cold extrusion press of the present invention to achieveconcentricity of the die ring 6 about the punch 20 through theengagement of the neck 9 of the die case 5 and the enlarged bore portion23 of the guide member 11; the co-axial relationship of the punch 20 anddie ring 6 is attained through contact of the stopper blocks 8 of thedie holder 2 and the stopper blocks 16 of the flange 12 or the pistons30; and the alignment of the punch 20 with the workpiece A is obtainedthrough the use of the assembly 28 which is vertically movable withrespect to the punch 20 during the forming operation. These featuresenable the press to perform the extrusion without distortion or bucklingof the punch 20 and, therefore, to produce cylindrical articles withsuch a high degree of precision that the products can be advantageouslyused in their various applications.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventiveprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

1. A press for cold extrusion of deep-holed or bottomed cylindricalarticles including a lower die, an upperdie movably displaceable in thevertical direction toward and away from said lower die, said lower diecomprises a die holder, a die case located within said die holder and adie ring positioned within said die case and secured within said holderby said case, said die ring arranged to receive and hold a solidcylindrical blank, said upper die includes a press ram, a punch mountedon said press ram and arranged to be forced into the blank so that theblank can skirt up around said punch and adopt a bottomed cylindricalform, wherein the improvement comprises a guide member for said punch,means for supporting said guide member from said press ram for movementwith said press ram, said guide member arranged to engage said die casefor maintaining the alignment of said punch and said die ring, meansassociated with said press ram and arranged to apply pressure downwardlyagainst said die holder, and means laterally encircling said punch forvertical, slidable movement within said guide member for preventingdistortion and buckling as said punch is forced into the blank in saiddie ring.

2. A press, as set forth in claim 1, wherein said means laterallyencircling said punch comprises a punch guide assembly which includes apunch guide case positioned within said guide member and spacedlaterally outwardly from said punch, a punch guide slidably fitted aboutsaid punch and spaced laterally inwardly from said guide case, and anadjust screw laterally enclosing said punch guide and located in saidguide case for coupling said punch case to said punch guide, and meansfor permitting said punch guide assembly to be moved gradually upwardlyby the upper rim of the article being formed by said punch from theblank.

3. A press, as set forth in claim 1, wherein said means laterallyencircling said punch comprises a punch guide assembly which includes apunch guide case positioned within said guide member and spacedlaterally outwardly from said punch, a punch guide slidably fitted aboutsaid punch and spaced laterally inwardly from said guide case, and anadjust screw laterally enclosing said punch guide and located withinsaid guide case for coupling said punch case to said punch guide, meansfor permitting said punch guide assembly to be moved gradually upwardlyby the upper rim of the article being formed by said punch from theblank, said means arranged'to apply pressure downwardly against said dieholder comprising at least one pair of vertically arranged hydrauliccylinders and pistons each located on an opposite side of and spacedoutwardly from said guide member, a rack formed on each of the oppositesides of said guide member on which one of said hydraulic cylinders andpistons is located, a rack formed on each of said pistons opposite saidrack formed on said guide member, a pair of pinions in meshed engagementwith one another and located between each pair of racks formed by one ofsaid racks on said guide member and one of said racks on said adjacentsaid piston, one of said pinions disposed in meshed engagement with saidrack on said guide member and the other said pinion disposed in meshedengagement with said rack on said piston so that as said press ram andsaid piston move downwardly said guide member and its associated saidpunch guide assembly can move upwardly by virtue of said means forpermitting said punch guide assembly to be moved gradually upwardly forpreventing any interference with the upward movement of the articleformed by said punch from the blank.

4. A press, as set forth in claim 2, wherein said means for permittingsaid punch guide assembly to be moved gradually upwardly comprises afirst ball bearing fitted into and extending vertically within the upperportion of said guide member and a second ball bearing fitted into andextending vertically within the lower portion of said guide member, theradially outer surface of said punch guide case is disposed in slidingcontact with said second ball bearing.

5. A press, as set forth in claim 4, wherein said punch has a steppedconfiguration with its lower end having a smaller diameter andpositioned within and in sliding contact with said punch guide, anincreased diameter portion of said punch as compared to the smallerdiameter lower portion is located above the lower end of said punch, anda ring secured to said increased diameter portion of said punch anddisposed in sliding contact with said first ball bearing.

6. A press, as set forth in claim 1, wherein the inside diameter at thelower end of said guide member has a dimension sufficient so that itclosely laterally encloses the upper end of said die case.

7. A press, as set forth in claim 2, wherein said punch guide has afrusto-conical configuration and contains a plurality of longitudinalslits extending through its wall guide and provide a collet-typeengagement.

1. A press for cold extrusion of deep-holed or bottomed cylindricalarticles including a lower die, an upper die movably displaceable in thevertical direction toward and away from said lower die, said lower diecomprises a die holder, a die case located within said die holder and adie ring positioned within said die case and secured within said holderby said case, said die ring arranged to receive and hold a solidcylindrical blank, said upper die includes a press ram, a punch mountedon said press ram and arranged to be forced into the blank so that theblank can skirt up around said punch and adopt a bottomed cylindricalform, wherein the improvement comprises a guide member for said punch,means for supporting said guide member from said press ram for movementwith said press ram, said guide member arranged to engage said die casefor maintaining the alignment of said punch and said die ring, meansassociated with said press ram and arranged to apply pressure downwardlyagainst said die holder, and means laterally encircling said punch forvertical, slidable movement within said guide member for preventingdistortion and buckling as said punch is forced into the blank in saiddie ring.
 2. A press, as set forth in claim 1, wherein said meanslaterally encircling said punch comprises a punch guide assembly whichincludes a punch guide case positioned within said guide member andspaced laterally outwardly from said punch, a punch guide slidablyfitted about said punch and spaced laterally inwardly from said guidecase, and an adjust screw laterally enclosing said punch guide andlocated in said guide case for coupling said punch case to said punchguide, and means for permitting said punch guide assembly to be movedgradually upwardly by the upper rim of the article being formed by saidpunch from the blank.
 3. A press, as set forth in claim 1, wherein saidmeans laterally encircling said punch comprises a punch guide assemblywhich includes a punch guide case positioned within said guide memberand spaced laterally outwardly from said punch, a punch guide slidablyfitted about said punch and spaced laterally inwardly from said guidecase, and an adjust screw laterally enclosing said punch guide andlocated within said guide case for coupling said punch case to saidpunch guide, means for permitting said punch guide assembly to be movedgradually upwardly by the upper rim of the article being formed by saidpunch from the blank, said means arranged tO apply pressure downwardlyagainst said die holder comprising at least one pair of verticallyarranged hydraulic cylinders and pistons each located on an oppositeside of and spaced outwardly from said guide member, a rack formed oneach of the opposite sides of said guide member on which one of saidhydraulic cylinders and pistons is located, a rack formed on each ofsaid pistons opposite said rack formed on said guide member, a pair ofpinions in meshed engagement with one another and located between eachpair of racks formed by one of said racks on said guide member and oneof said racks on said adjacent said piston, one of said pinions disposedin meshed engagement with said rack on said guide member and the othersaid pinion disposed in meshed engagement with said rack on said pistonso that as said press ram and said piston move downwardly said guidemember and its associated said punch guide assembly can move upwardly byvirtue of said means for permitting said punch guide assembly to bemoved gradually upwardly for preventing any interference with the upwardmovement of the article formed by said punch from the blank.
 4. A press,as set forth in claim 2, wherein said means for permitting said punchguide assembly to be moved gradually upwardly comprises a first ballbearing fitted into and extending vertically within the upper portion ofsaid guide member and a second ball bearing fitted into and extendingvertically within the lower portion of said guide member, the radiallyouter surface of said punch guide case is disposed in sliding contactwith said second ball bearing.
 5. A press, as set forth in claim 4,wherein said punch has a stepped configuration with its lower end havinga smaller diameter and positioned within and in sliding contact withsaid punch guide, an increased diameter portion of said punch ascompared to the smaller diameter lower portion is located above thelower end of said punch, and a ring secured to said increased diameterportion of said punch and disposed in sliding contact with said firstball bearing.
 6. A press, as set forth in claim 1, wherein the insidediameter at the lower end of said guide member has a dimensionsufficient so that it closely laterally encloses the upper end of saiddie case.
 7. A press, as set forth in claim 2, wherein said punch guidehas a frusto-conical configuration and contains a plurality oflongitudinal slits extending through its wall in the axial direction ofsaid punch, adjacent ones of said slits extend from opposite ends ofsaid punch guide to a point close to but short of the opposite end ofsaid punch guide, and said adjust screw has a frusto-conically shapedinner surface to engage said punch guide and provide a collet-typeengagement.